Ladder for floating roof tanks



Dec. 27, 1955 E. E. LA SPINA LADDER FOR FLOATING ROOF TANKS Filed Oct. 6, 1952 INVENTOR. '"fafr/a [d5/mm HTTR/VEY United States Patent LADDER non rLoArrNG noon ranas Edoardo E. La Spina, Brooklyn, N. Y., assigner to Socony Mobil Oil Company, inc., a corporatinn of New York Application October 6, 1952, Serial No.. 313,219

1 Claim. (CE. 228-1) This invention is concerned with a ladder for oating roof tanks for the storage of light petroleum products such as gasoline and the like.

In order to prevent losses from evaporation, light petroleum products such as gasoline are frequently stored in tanks equipped with roofs which float upon the surface of the liquid, and move up and down therewith within the tank, somewhat as does a piston in an engine cylinder.

Access to the top of the roof is necessary for gauging and other purposes. To secure such access it is customary to provide a ladder, or stair, pivoted at the edge of the tank shell, with the lower end provided with wheels to run on a track mounted upon the surface of the roof, or other means whereby the ladder is self adjusting in position and effective vertical span to accommodate all positions of the roof. This arrangement is satisfactory with tanks whose diameter is great with respect to their height, but impossible with tanks whose diameter is less than the height between the tank rim and the roof when the roof is in down position.

This invention is directed toward the provision of a roof access ladder for tanks where the diameter is less than the vertical height between tank and roof when the roof is in the down position.

To understand this invention, reference is now made to the drawing which is attached to and made a part of this speciiication.

In the drawing, Figure l shows a tank, having a floating roof, in which tank a ladder or stairway made in accordance with this invention is installed, and Figure 2 shows an end view of the ladder, taken at the roof end, and should be read in conjunction with Figure l.

In Figure l, 1i) denotes the side wall of the tank, shown in section, and 11 denotes the upper surface of the oating roof. Since neither the tank nor the roof are any part of this invention, neither are shown in any detail. At the upper portion ot Figure 1, there is shown the ladder in full folded position, as assumed when the loating roof is at its highest position. The ladder consists of two portions. The rst portion is composed of side rails 12, carrying rungs 13, and handrail 14. This portion of the ladder is pivoted at its left hand end to the tank rim by pivots 15 mounted in brackets 16 which brackets are atiixed to the tank rirn. At the opposite end, the side rails 12 carry anged wheels 17, mounted upon an axle which may conveniently be formed by 2,728,512 Fatented Dec. 27, 1955 ICC to each side a distance greater than necessary to support lianged wheels 17, for a purpose later to be explained.

The lower section of the ladder consists of side rails 19 and rung 20 and aixed thereto by proper fastening, such as welding, are two rail pieces 21, adapted and spaced to form a track upon which ilanged wheels 17 may roll. This portion of the ladder is provided with handrails 22. The right hand end of this lower portion of the ladder is pivotally fastened to the tank roof by pivot pins 23 in brackets 24. At the left hand end of the lower portion of the ladder there are provided hook plates 25, notched to receive and hold the ends of rung 18 which extend beyond the anged wheels 17.

As the roof moves downward, the angular position of the two portions of the ladder changes, and the upper portion slopes, while the lower portion rests upon the roof, horizontally as shown in diagram at '12A and 19A, while the lower end upper section moves along, supported by its wheels 17A rolling upon the track rails 21A.

As the roof continues to move downwardly, the wheels reach the end of their travel, 17B, when the roof reaches a level 11B, and the extended axles 13B become engaged in hook plates 25B.

Thereafter, as the roof continues to move downwardly the ladder becomes a hinged structure suspended between pivots 15 and 23, and finally when the roof has reached its lowest position 11C, the ladder parts assume the position indicated at 12C and 19C.

Thus there is provided, at any stage of roof height, a continuous ladder or stair, extending from the tank rim to the floating roof surface, which ladder is suiiiciently firm and stable to support any trallic necessary between these points while the tank is in service.

I claim:

In a oating roof tank of less diameter than height, an access ladder for the roof of said tank, said ladder comprising two sections, the upper section being pivotally supported at the rim of the tank side wall, the lower section being pivotally fixed to the tank roof at a point diametrically opposite said iirst named support and arranged to rest horizontally upon the oating roof in the upper range of travel of said roof, the free extremity of the upper section being provided with flanged wheels on either side, the lower section being so formed as to provide tracks at either side upon which said wheels may travel, the free end of the lower section being provided with socket members on either side, the free end of the upper section being provided with means for engaging said socket members when brought into contact therewith thereby providing a hinged two-section ladder which assumes a substantially straight form when the floating roof is at its lowest position.

References Cited in the tile of this patent UNTED STATES PATENTS 1,636,963 Iagschitz July 26, 1927 1,945,531 Kramer Feb. 6, 1934 OTHER REFERENCES Horton Double-Deck Floating Roof, Bulletin B, Chicago Bridge and Iron Co. 

